The Gemara, Menachot 43b, states that there is an obligation to recite one hundred berachot each day. This article will discuss the reason for the obligation, its parameters and special circumstances that arise.

The Source for the Obligation
The source of the Gemara's statement regarding the obligation to recite one hundred berachot each day is from a Beraita quoting Rabbi Meir. Rabbi Meir supports his statement from a verse in the Torah (Devarim 10:12) which states "V'ata Yisrael mah Hashem Elokecha sho'el me'imach" (And now Israel, what does God Almighty ask of you?). Rashi, Menachot 43b, s.v. Mah, explains that the verse serves as the source because the word "mah" is read as "me'ah" (one hundred). Tosafot, ad loc., s.v. Sho'el, suggest that this verse serves as the source because there are one hundred letters in the verse. Tosafot also provide a number of explanations.

Tur, Orach Chaim no. 46, notes that regardless of the explanation for Rabbi Meir's source, the verse is only a support (asmachta) for a rabbinic enactment. Tur cites R. Natronai Gaon, that this obligation was originally instituted by Kind David during a certain plague that was killing one hundred people on a daily basis. Kind David instituted that one hundred berachot should be recited each day and this caused the plague to cease. [This idea is also found in Midrash Tanchuma, Korach no. 12, with one slight variation. According to Midrash Tanchuma, King David himself based the institution on the aforementioned verse.]

How to Tally the One Hundred Berachot
The Gemara, op. cit., states that on a weekday, one should have no problem reciting one hundred berachot. Beit Yosef, Orach Chaim no. 46, explains that there are nineteen berachot in the Amidah, which is itself recited three times each day, for a total of fifty-seven berachot. Additionally, there are thirty-two berachot recited as part of the morning and evening prayers (including the berachot on tzitzit and tefillin). The count of one hundred is thus complete so long as one recites eleven additional berachot associated with eating. [Beit Yosef assumes that one normally recites sixteen berachot associated with eating. On the minor fast days, one would be short a few berachot. Beit Yosef suggests that one should don talit and tefillin at Mincha in order to close the gap. This is practiced in certain Sefardic communities.]

On Shabbat and Yom Tov, there are only seven berachot in the Amidah. The total number of berachot recited during the Amidah prayers of Shabbat including Musaf is twenty-eight. The Gemara states that R. Chiya b. R. Avia would eat additional snacks on Shabbat and Yom Tov in order to reach the count of one hundred berachot. According to Beit Yosef, it is reasonable to complete the count using food items if one factors in the additional berachot recited at Kiddush and Seudah Shlishit. However, other Rishonim are of the opinion that even with the additional snacks, one must still rely on other factors in order to bring the count to one hundred. Shibolei HaLeket, no.1, cites one of the Geonim who suggests that one may count the berachot before and after the reading of the Torah and the Haftarah, adding an additional twenty-seven berachot on Shabbat and twenty-three on Yom Tov. Maharil, Hilchot Yom Kippur, suggests that on Shabbat and Yom Tov, one gains an additional twelve berachot by reciting Ein K'Elokeinu (see the comments of Maharil for the explanation).

The most difficult day on which to recite one hundred berachot is Yom Kippur. On Yom Kippur, there are no berachot associated with food. There are thirty-five berachot of the various Amidah prayers including Musaf and Ne'ilah. Additionally there are thirty-three berachot recited during the rest of the prayers (including Shehechiyanu) [See Mishna Berurah 46:14, for the exact tally]. If one counts the berachot on the Torah and Haftarah, one can add an additional twenty-nine berachot. This leaves the number at ninety-seven. Magen Avraham 46:8, recommends reciting a few berachot on smelling various spices in order to complete the count. Mishna Berurah 46:14, adds that one may also count the beracha of Asher Yatzar (the beracha that is recited after one uses the restroom).

May One Create Situations that Allow for Additional Berachot?
One solution to complete the count of one hundred berachot would be to try to create situations where one would be required to recite additional berachot on food items. What stands in the way of this solution is the concept of beracha she'aina tzricha (reciting a beracha unnecessarily). The Gemara, Yoma 70a, implies that it is prohibited to cause a situation where one recites a beracha that could have otherwise been avoided. As such, Magen Avraham 46:8, rules that one should not create situations that would require one to recite additional berachot in order to fulfill the obligation to recite one hundred berachot. In fact, Magen Avraham 215:6, cites the Gemara in order to reject the opinion of Shelah that it is permissible to cause a situation where one would recite additional berachot in order to recite one hundred berachot.

When Does the Count Begin?
Regarding almost all Jewish events that relate to days, the day starts at night and ends the next night. Ostensibly, the same should apply to the obligation to recite one hundred berachot each day. It is evident from the comments of many Rishonim who deal with the problem of how to recite one hundred berachot on Shabbat and Yom Tov, that they assume that the count starts when the halachic day begins. However, there is an opinion cited by R. Yehuda ben Barzilai, Sefer HaItim no. 195, that for the purposes of the obligation to recite one hundred berachot, the count starts in the morning and finishes the next morning.

R. Shimon Sofer, Hitorerut Teshuva 3:502, queries regarding the berachot that are recited if one accepts Shabbat early and recites the Ma'ariv prayer prior to sundown. He concludes that if one accepts Shabbat early, all of the berachot recited thereafter are counted for the tally of Shabbat. R. Betzalel Stern, B'tzel HaChochma 4:155, also discusses this issue and concludes that those berachot are counted for the previous day. According to R. Stern, if someone accepts Shabbat early, he must replace an additional eleven berachot (seven from the Amidah and four from the berachot of K'riat Sh'ma) from the standard tally. Additionally, all of the food-related berachot from the Shabbat meal will not count if they are recited prior to sundown. [Perhaps one can deduce from the widespread practice to accept Shabbat early that common practice follows R. Sofer's opinion. Otherwise, it would be extremely difficult to fulfill the obligation to recite one hundred berachot.]

Are Women Obligated to Recite One Hundred Berachot?
R. Shmuel Vosner, Shevet HaLevi 5:23, notes that one can infer from Beit Yosef's tally of the one hundred berachot that women are exempt from the obligation to recite one hundred berachot. Included in Beit Yosef's tally are berachot that women do not recite. If women were obligated in the mitzvah, Beit Yosef would have mentioned that women must complete the tally with snacks on a regular weekday. R. Shlomo Zalman Auerbach (cited in Halichot Beitah ch. 13, note 2) also rules that women are exempt from this obligation. He explains that since many of the berachot necessary to complete the count are berachot that women are not obligated to recite, one should assume that the original institution never obligated women to recite one hundred berachot daily. [See Halichot Beitah, ibid, for a discussion as to whether the concept of mitzvat aseh shehaz'man gerama (the concept that women are exempt from positive time-bound commandments) is applicable to exempt women from this obligation.]